1. Field of the invention
The present invention is concerned with a method and apparatus for repositioning discrete articles such as segments cut transversely from a continuous moving web of material. For example, the present invention has utility with respect to repositioning discrete abutting segments of an absorbent material cut from a continuously moving web of the material, to form a spaced-apart array upon a continuously moving web of substrate material. Such technique may be utilized in the manufacture of disposable diapers, training pants and incontinence control garments generally.
Articles such as disposable diapers are generally made with a liquid-impervious backing sheet on which absorbent pads are positioned and covered by a liquid-pervious topsheet, the resulting composite material being cut into discrete articles. In many cases it is desired to place the discrete absorbent pads in a spaced-apart location onto the liquid-impervious backing sheet (or onto the liquid-pervious front sheet), which serves as the substrate upon which the absorbent pads are placed. However, the discrete absorbent pads are usually cut from a continuously moving web of the absorbent material or material formed in place, which produces a moving array of pads in an abutting relationship. Consequently, a means for placing the discrete absorbent pads onto the substrate web with a selected spacing between adjacent webs is required. In other applications, it may be desired to reverse the procedure, i.e., to place individual ones of an array of spaced-apart articles into continuous abutting array or to change the spacing between adjacent articles from one distance to another distance.
2. Description Of Related Art
U.S. Pat. No. 3,386,558 discloses a feeder mechanism in which a device having fixed, radially extending arms is cam driven so that, as the device rotates, pneumatic suction cup gripping means at the ends of the arms travel along the path indicated in FIG. 2 for removing folded carton blanks 5 from a hopper 3 and depositing them atop stacked containers C moving along a conveyor belt 6. Rotationally eccentric movement is provided to the means 19 which carries the fixed arms thereon.
U.S. Pat. No. 3,834,522 shows a transfer machine comprising a turret having a plurality of radially translatable carriages mounted thereon, which carriages are fitted with a suction cup 46 (FIG. 2) for gripping a container. A cam track (85 in FIG. 4) moves the carriages radially outwardly during rotation so as to enable the suction cups to grip the container at the unloading station, then retracts radially inwardly for transporting the container, and then moves radially outwardly to feed the container into the stacking device. The turret provides for intermittent movement between the stations to allow sufficient dwell time for the freshly printed containers to dry.
U.S. Pat. No. 3,494,001, shows apparatus and method for making sanitary napkins and discloses at column 10, line 58 et seq and FIGS. 11 and 12, the use of paired rolls operating at different peripheral speeds so as to separate individual articles 116 passing therethrough.
U.S. Pat. No. 3,827,545 concerns method and apparatus for changing the spacing between discrete, flexible web products and utilizes, as illustrated in FIGS. 1 and 3a-3d, a variable-speed pinch roll 14 positioned between respective conveyor belts 12 and 16, which operate at different speeds. The peripheral speed of the rolls comprising pinch roll 14 is varied between the respective speeds of conveyor belts 12 and 16. The patentee refers to positive control being exercised on the transferred object (column 7, lines 19-20).
U.S. Pat. No. 3,847,273 discloses a transfer means comprising a rotating drum having radially extending arms which carry gripper means for orbiting about the drum axis of rotation, as illustrated in FIG. 1. The radial arms 26 are constant radius arms which rotate about their own axes to pivotably turn articles 12. Consequently, changes in spacing between adjacent articles are effected only to the extent of the difference between the length and width of the individual transferred articles.
U.S. Pat. No. 4,394,898 discloses method and apparatus for providing balanced stacks of diapers by turning alternately dispensed diapers 90.degree. to the right and the remaining alternately dispensed diapers 90.degree. to the left, so that 180.degree. rotation is provided between adjacent diapers. A rotating drum having fixed, radially extending arms carrying pads which engage the dispensed diapers is provided. The arms rotate about their own axes.
French patent No. 2,490,601 shows a rotating turret 15 equipped with fixed diameter radial arm and adapted to remove individual articles from a stack 5a thereof to place them onto a conveyor belt 1.
U.S. Pat. No. 3,374,752 shows a transplanter for handling paper cylinders containing seedlings which are transferred from a conveyor belt 10 to members 22 mounted for rotation so as to deposit the seedling cylinder into a furrow opened by a plow blade ("opener") 3. The members 22 remain at a constant radial distance from the axis of rotation.
Various types of transfer mechanisms are exemplified in U.S. Pat. Nos. 3,887,605; 4,164,996 and 4,471,865 and in French patent No. 1,113,360 and Japanese patent publication No. 55135026.
Copending patent application Ser. No. 673,064, filed Nov. 19, 1984 and entitled "Method And Apparatus For Applying Discrete Strips To A Web Of Material" discloses radially extending and retracting shoes employed to transfer segments of elastic strips dispensed at one linear speed onto a continuous web traveling at a different linear speed. A change in the orbital radius of the shoes during their traverse of the orbital path changes the orbital path speed of the shoe to accommodate the different linear speeds.